The present invention relates to a thermosensitive recording material and more particularly to a thermosensitive recording material suitable for use as thermosensitive-recording-type tickets, including magnetic tickets, and thermosensitive-recording-type labels.
Conventionally, there is known a thermosensitive recording material comprising a support material and a thermosensitive coloring layer formed thereon, which coloring layer contains a leuco dye and an acidic material. The thermosensitive recording materials of this type are widely used, since they have many advantages over other recording materials, for instance, image formation or printing can be easily done and the images obtained by heat application are clear.
When such conventional thermosensitive recording materials are employed as thermosensitive-recording-type tickets, such as passenger tickets, coupon tickets and commutation tickets, or as label sheets for indicating product names, numbers or prices, etc., if the front surface of the thermosensitive recording material is kept in contact with a plastic film, the images and letters formed on the thermosensitive recording materials lose their color and become illegible due to the action of plasticizers, such as dioctyl phthalate and dioctyl adipate, contained in the plastic film. That the recorded images and letters cannot be made permanent and will be lost if the storage conditions are not appropriate leads to low reliability of the tickets, the label sheets, etc., made of that recording material, and causes various troubles to those who use them. This shortcoming has been a significant hindrance to employment of thermosensitive recording materials as tickets, including magnetic tickets, and label sheets in practice.